SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52172ca90c96507923cf2a8f84736679945331be256ddd4d3f0905aa493bc44a' 
  AND token = 'mvAamhZDo3Mvlevn/xHYmmSq73K4QsVbvJrC7QHY8fk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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