SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a42544e8e9a57738a62a13356d3384d2a4eed93badb4cd7b2e80f412c150a43' 
  AND token = '9q/SYXzVq/EL1uyq0ak8UhdIndU2Z9Md5bfsZ8iFrqQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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