SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'c5a31d10698509521ef871878d3943d32642249a45a9813f42cef5781b968f11' 
  AND token = '/lZcCw+LxtlhZ+22Vt88EJPWUcc87jPMwKMT9OkFPjc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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