SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5960dc7b072e7a78d6f519d90d5248398c6c0303c30eefa74dd5cdadc54c549f' 
  AND token = 'YKpkyrcqCWzBuLhhcaMS6HTJ8rQOvwhbAF/awrAHlyk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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