SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b76282ad402643fbeb98fae63359d75f9092e96101b6f2178d32345fb121bf8' 
  AND token = 'm+9z1lsbFsybMXxszApGnG3YNhd9K/muJbGeGlRlZ4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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