SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '389409a63a5c13b9e5b5cf353289e724d71dc0ae6fdc1c43b055065b3b6ed474' 
  AND token = 'JeWIuKNd9q+dJm0a1nFC3BuvzAhgoGY+Gt1aWJbqvuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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