SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '878b5d99a081c77c764bce4cf1dff18ab00986c57aafcb464328c3338d8f0c36' 
  AND token = 'imBpJ2Q67VQSKeqOiwKWNrkJhDSIPK7dTvHkRYAx5Qo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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