SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5cd637685fe8b3c7ab52ac6b81957383fe99262105e0306bfc239006573192f8' 
  AND token = 'UFPOU35Ue8OrO7colA88cxnK4NPfEgGt/CDc17lDUqE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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