SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'cdbc3b12ab4628ca1278f0efcc92a1a5e9017f36c4d5bc28c6959dff4bc699e6' 
  AND token = 'RZ9cSf5wjCV4NWWhsz5xJ+TVDAg/kguhgrifq7UK70o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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