SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd619716409df1c938c8e974b9715daf53f47af808d3e2238e5db334d37dcab3' 
  AND token = 'PnPCkHW47gTbnd/+qwcLfntrz4MKCrsYCXyk+dxug/Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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