SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ad17dbb78520e22b8c38970f9988655781b6d883a4f988a677699f304cf3fb9b' 
  AND token = '22FdAIqjgPQBamjZV11EXf+O/no6utcmAoT/JKNvBVE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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