SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '35635106c442758182074258cbd2eba206d3154160cf9d5e3ff91b2d79653519' 
  AND token = 'HyLYXIzwkI4Je2qBXb8ahJm+XP7oSoqOXoieuvAmID0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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