SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '988db91b8fe15986e1200d5858324e36086b6f567f5fba73b19de537ccc5eacc' 
  AND token = 'w4X55Idrnedf1/Ncxli7if768ign8xlMGwfBuVtCxuw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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