SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '656d1a9762adfe76f9ae8d24d939399f6f3971a4bc389e022201d0a2d213cbee' 
  AND token = 'SM37lrT+kKzHTModvkbB/mWHXe/U1bnSYyIo83IAN3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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