SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '61ef5e458145a9461604b48c9f70c08a636fe4db738b5214a4c806a41a596a6e' 
  AND token = 'E5ZNe8xtTtjHWB1L9jRVS2izmYgXEMBuqA6FdkRbOMA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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