SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dc69a0faf47be54672dec8d762bcac1a01464e008a66dcf413f73315698f919' 
  AND token = '8SOBxd/xrEk/Yi+WDUQ3jUvJ8qVaEYK3W1K2rzzGAd8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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