SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3d457f4d551319b7e10a6a08e5db6866863d29d261fcf3faebb7faed0ba58bf' 
  AND token = 'AHouSK4RxaouKIxL5aVNboUyFlWQRJkitYCJO59SReE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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