SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a9942308bbadf71b214bc9766a1a1ac1ce126e5aae5043005d076c2cce07f80' 
  AND token = 'yBxFLYsw99l8HykRJTJ4VENawtVgr7PX1/YSHYWbSdY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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