SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd18d163787354557a301a96b5e870280efeae15a57715f2d062dbb0e1bc83bd' 
  AND token = 'zvUU+zYS5agr56vYV5AHf+rvIvv7PqsJjI123qU5JZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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