SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54ee1c5c51c5bc931433e88cdddfafb76a00188d81d84294d40608f8e812f8b3' 
  AND token = 'vmzF3+ZqUvC6zPHSQpjjrezzRaWqtyyDjsQhAmuppgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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