SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6f605312648574dcd5aeac38ddc0ab004f315ac1cff362b70da6964735854dbe' 
  AND token = 'GxZxogBHIR2I9HduQNVS79R87EAP0qUWBk3DYyEXYL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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