SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f1fedb0b3171a50ba031b898bdb8626cd511872732149d612c1e4cd5d4f2ff4d' 
  AND token = 'ZtqRFbb4EWTa8mHnCW8wTGvAFCnpWWs5LUKwGEzAmU4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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