SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '867ef20d1a7567ccd402624d288166e6edc775f95077d869d5f0eba535ca67fd' 
  AND token = '4piafbknx1sznMvtCrwDNXyabxOt5b7ULBNa6hiasc0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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