SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4b0053b84840a652cf891639440b49cc6b28d31f766891d1fd9d2d43d7e9169' 
  AND token = 'Muko5DSLXDGy5UjucdpRFU8FSeii1WClDzJRXWoISSs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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