SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '48e71eb83dea936e49b322141aeb793273c4524186e798a61762dc35e1b1dff6' 
  AND token = 'taxVJCqlbkOIIwnPv7I0QpubPouQ5c5IeCwl1OiMB+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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