SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52a19e23219f7446a82058c3d23988503ccbef53246355eaebf09f3fe15021dd' 
  AND token = '3uQZjE8HEY/wNS8ZD+b7J2tv/qL9t9YIHXQfFgFQVuk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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