SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '31d2755e5b02e8e33ea04b8c739f495c91e935c76023b6df8459438fa0fc7da7' 
  AND token = 'am99IvHLk1pfR7MFBnj8rF+5GapmqUVAoQZ02Xfh21g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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