SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a8a2603bb56a8f727bb8c90a832336f732d82452f7c4ba99a7437b631235b311' 
  AND token = 'DF1NNt9Y2/gyFV4brnQRwSDk9A6och/XssPeSgITHCQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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