SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3fee088d3069e63b40c553631eb619f0868f9f5cb0faae94677e94bb1636723' 
  AND token = 'LkVNxhh8jfzVaFl3qNGX+RyyKRrKMsqemwLyuhumA9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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