SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b34816ffddaa8a73ccaff4bcf8d0fb0fc7b5c9d8de121399c6f2f982466c6eb2' 
  AND token = 'gc4qls0ymNg7wd1jfcc7SL+5CTjwTv7nJGmgyoGdRwM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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