SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b843be23f20eb36d4450aafba3d54b3502a712ff12b34e9aa00ea364637d8cf6' 
  AND token = '8VGRf1ydIvYTTzH+YLNpsEZKwVrh+q2Eyus7ny/ygSo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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