SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff4710f99f64db0490b598f7c65c1ab109af3b2ad3136b7c5aebe0e6fd2b4873' 
  AND token = '26RsUzRP8YmhRzw9zUuY1VDw5B6LIlOup2WuurHuZ5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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