SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3bf751a43832e3f3bafc2872d34ea51c52b5ea5fbb929dd14b924fee26a54d6' 
  AND token = 'Spy9pCW9l2uyeXwxTJFv7hOt0dT0ZGS1SmIZhMOtrOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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