SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '039ab32ddd6177b17b5104dd29d9adfa66336f450978957b3e7e7cef6b1c3db1' 
  AND token = 'kQLmSmBl5DZ5OKYrmVcyyfgCFlEwN+yUD/q9qvyVovk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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