Sandbox

SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c51e7f45c51d9e741bd54787eed38ab97401312211f9a5a66dfe2e7e2b46ec49' 
  AND token = 'tuCpYnPd1gSvRpLYWxXzHKj1VsKX6cgxiF+EFDJryiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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