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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '873b692f78a95c223e69e6e3cf74f9e3686cfede3751d0cccc7d7e66b164b405' 
  AND token = 'CggNw+Y+NXOIhCtcRRBDXRS0kqtu7BAwmSekp8a5mYE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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