SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c1f3592a234ccaedbb9fc8c6936769a2953366f331e6ea316fb682ffa79465c7' 
  AND token = '2GFmboKafg7ljRDHUHOoklhgrYwp3xer7BlKstu98lw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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