SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a8042df0526ead3d1982e0be40ebbc9c7d55f33159d05c66e8f35226eb7fcea6' 
  AND token = 'zR1hGOdojqDx+e0KLVZBwgfIMJ9e4XqskuHwwm6wQIo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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