SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3febf28b30169b309c08f200df94dbdfe500709511701c888b9dd60de1da3cb' 
  AND token = 'ZqTWtwCOR3sZN4nVAO9BhAtvLqIr5wYbNuO9yew3REA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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