SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc19e173cf83829a7cabd4a356cc56554f9c7e94ae4eddad8b15523beb518331' 
  AND token = '1zBIC1uXW+V4PDVeZjqmSYz43K+Uv5fwZMfa0V9mU2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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