SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20e2839c7824a81dde9d0508c90531265fcb64a873e35fd1f7e30076819f0d5d' 
  AND token = '8pHWydRG7BKW7KzbeiwiJgdrzgnOmHYwJa/svM5ZG3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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