SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '865c938dd7880724305a4314d41bef397908f7f532ca6a5d24fd4f9f906aa509' 
  AND token = 'aV1WSJ6uebgQzZ+CEgXt1yzPw+b3/tTwSNgCcpGZevM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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