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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27bea49d289adfd839d620624264f03953a0de4872f30bda218e9bd8c213bbac' 
  AND token = 'ETRqyFBmgrIBX3SleNSfTOMU8VobQhBt3ESHQquuNVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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