SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '676aa44bf7890b1389e7c823686b845f3132547b3c6e5a43ee077610fb2bbb0c' 
  AND token = 'JQ8Zw+p7XC1bt/mV+PGNFXeKOY3i4i1vqmOjMPF534g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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