SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '294dca11f7cb4437f38b11d744273a809e62a3a5966bce62f6155ac10201effe' 
  AND token = 'jva27kM13xO+8X6vTZFgRTQhjqelJltXKg0aOQ3c9qA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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