SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b3222e9cd7c6378a6442419529d234ae69577c62e8bae3b4ac82f3bd6d73b14' 
  AND token = 'QP7yfPcXw3DG1bqUAAh2n35tfV+NYzIHo1Z1nMvn4DQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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