SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e4a191fc61f046f42ddddec6eeccec71c2d9d8c98832ec76488a0ca5be53a27' 
  AND token = '8MLHuIDwYhOjwm5pKot4FTirdzghWYTwlL4/XeBsItE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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