SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8ae6cd9813a5096c9b82dd5af893709af9fc5f62efec237a3ebbda6ef9e046a' 
  AND token = 'fwjvO3Fa+VWBwdVQfsQb28C+axUyPYgNpqoLEb8b0PQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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