SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fb917d52671ab85b097310f28c8f03242bb835500fbcc2db10612c0a5599d36' 
  AND token = 'tjKqkOOR7QdZIiaCuB38iywyeANYnlC0a3VRUuVVsgc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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