SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5acbd612e8f2a97af6798e0513547f34d4679244ed8283368f07fd2650a5ca1' 
  AND token = 'mxL9qtHmCSfwUV+6zVavSZLbpxiAkdwnOfwVNMGo3Aw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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