SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81a289bab36f62c3eaafc0d21ffcf8715c852e9dd75fb74ddaf835e2c57de6b1' 
  AND token = 'esQ1Zk+wmwsUANIeDqeyV3sACHlrVENXD/yoATFDqws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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