SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8ef357f63e2f88e6a08137bc7a74115bdc4b516b696be6b82529080643f5aee7' 
  AND token = 'yIHPE8Nt5UJgFZf+HGhWw3DTLe+LzXOo+9O2ErholZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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