SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77e4490caf06459f287fc4b4da8ecd2c211e351e0264688a51084527072555f2' 
  AND token = 'zG3sJR3vyiIuDmlL1BH4EgdTeGP9AD5oGrXjIXba+G8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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