SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4998b5522cd2c79e67b5991fac175436eec986c515b56855863e2456b3edd7cb' 
  AND token = '75zHdPamKeky2z0EjEXKmlZkurKez2wyLMPHiKfLPk8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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