SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6426747160da4f62f115894eff82fd09c90ec502cd57d16d5a8e888e882d7d20' 
  AND token = '6H/j5WsYZy9mhGYwLdHxGqEiNtnxcL6mraYYHuhfZYo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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