SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6966ce603b445f3463db7e69592fb6f13c8ad0ee827266b482a31f9081387d7' 
  AND token = 'VEfdxrr4tKIWMTVsYayAwWgG3VUYtqXvxu14BBiueXU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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