SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1ef7a7efd8ceae2c61f25a1048a3d66f9b7859286cb6c27fe9c15848e0e335d9' 
  AND token = 'u8ZiEmBwbY/In3vdAR6qxIr7OSdwO3WRZEXpREOAoA4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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