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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a03b357043e3d6e485ff2ec86e6a7a7f6c4ef2c49ba8904f1f2cde8ac993a8d' 
  AND token = 'Sp0jF8jOs0Z1+rDHJt9sou1XgLXtc52Mg/JUt7//+Mk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}