SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '53a7c2be75fad230bcb7dca4092f21492f8b7b66616a9ce8276eb29eee3864c5' 
  AND token = 'x5pBPhCcG5jPi/sT/sgGYhRUvyytQK1XDfjCQ6Kpgx4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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