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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71f5bf293b37b2b90e9e604644460a427de8f5bae59c1866520e0e1cdcfd79fe' 
  AND token = '4BwIll4PTbXq25G0u44CHoWwNQAHN5rv4Ed30a9g/3o=' 
  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"
    }
  }
}