SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88962c6069421a8fad1c75c3a8088fd940a247c968b037738078558a2cc7fe33' 
  AND token = 'IiRG1ETSy30Z4FcjJ2j2cFfGD3cawsr09/VOTbrQRZw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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