SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3998d1cbcb58ca963e4017c1ee20ce443a354a65b40597ef5d1d3222ff33d697' 
  AND token = 'vGtZF1CoawohmTOEnXAb/wm+y3pMcTC7Y4uO7z6B/uw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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