SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff05bbca5bdd86bad1d55460192035583a9994f941080ef2505ad41a7da2ad0a' 
  AND token = 'OE+yObwVhFUcAnW99ZfPtRGlqagYCSWKgNvQ+2hYO4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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