SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a845b21baa6a3608b03cc853e93ccddb6799624e32a036fb3f8a6bcdb7e7cd08' 
  AND token = 'dEce8NfH+3CRqk0ox82Zmto+vgJOGaHdiP8/UN5UgWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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