SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd1fbc768285d631debc9c5a89288697cd89644bb15e187cc9ec219390ddc68fd' 
  AND token = 'mRqQyncOqfYoUzv2BrMXFJqd/UXB5Zribywjo3wItLc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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