SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8c9d672b2f58a8e97bfd2a44772b4c81cc9d9a74db9d4bc98f11615bbf929b3' 
  AND token = 'RAiCJFBly/9qUXgXsJM7uLNN3qoKi5Q7v/KrvHyP6/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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