SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1851d04966d37bb6b536c332f2dcd4b87ed602831bb8b5364211073a4d2336b' 
  AND token = 'z6O+CLHwk7B/xKoCDWxDpkpY7wmxF28+Ep2MggVnBQU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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