SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1527bba5401769ef3e40731d78184c7166fd1db1835ac2b18b45631d9a129683' 
  AND token = 'ustZEHMDKt42VOB7ES85xkdeip/fIOppaZnx+ADKoJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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