SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '27976a9af0a94aa0ad1db5de51da7e943cb2086f148d7e141d7e9d28f65d8d3f' 
  AND token = 'pCYrZinwVoinSO7csMm9DJy6d7ZdBcZNVzOMEWoPmYA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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