SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '836d1b17f235521a5d96000c3cb95c3cbf3c855de353bd82cea338aa8460747c' 
  AND token = '8c1pWeXdgODtRblibquldkvfLDU2KpGWFJkl/dfxsjU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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