SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb26fa620de91ac9354073b75a9c11351be306fd2042dc0adb83f157c36db45d' 
  AND token = 'xKgd+AUJFNQiTgwRBoHKBwmFfvdOAbNVh6xCz30GWEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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