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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df3f7bfc701c0adb3ab6770f1bc75de0bf39f098e216a519f4ef56d7967191ff' 
  AND token = 'UbuRqbj6u28AzXT6f5VTCHmqwIGuavrQPuRRt1/ykuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}