SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e6e8a58f8f7c984d06dd04c4c348634f573e123fc1f9405c660638a71a4f48b' 
  AND token = '+BLUQCAfSWVZ26mooxn3qbriD/SrunIbCqg2+PmRZbw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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