SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42c4f5011ff3d67ac3278720a7c1e50c7e40668204cd157bffab59251bdb14d1' 
  AND token = 'g8B/IGxK2EZ0m47wNgSHUGAYefQs+HHoZ2rBovp9Mxs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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