SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5899f70c9486500f27ca68f075197086de1a1f3e87faea461ec0a81845a48506' 
  AND token = 'Sjn+YpfBJoot09xflOYo5dgBBu3voNPTMQFuMOUq4eI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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