SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6e1ccaa1e3c4ae61ddd3a67c81516105e4fc62ca21585d82c4c7943cf6ca19d' 
  AND token = 'Xoq422vAQEUDyd2Wz+qUKMFg80DqaMevFh9oQwpC0Pw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00050

JSON explain

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