SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a72a0b8138a317702958746eddbbad14b98ea101812afff223d02707a2e52bb6' 
  AND token = 'AXxhBuKJ5PCoxZ7cQswjS8Kko8w+gwV2GBeXZ7FJ1hU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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