SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2137c268f9bf3ae8cf0288579378b999eb90ad5815fed4e136e1b10bad7ac735' 
  AND token = 't96+vh1agMqWVOF/9us9vmp0O4p3biK6zZoGwtNVAOY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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