SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ffaaf2e30bcfea5ba6b0356f92b900f336a55c1a6e2e279a915702ed3ea4a6e' 
  AND token = 'CR69JIJY5PhjztdOk9KJjyPEV1y7rZYXnJZpw/ldQXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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