SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '48300ad30063f1f956a437381dad1faa811a21d3259a2513afb479dbd1ab3d8b' 
  AND token = 'lEt8RpF21DiJdR0VGXgIVFQl1OdCofzd+YeApoa4bRQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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