SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f685fe07c568bbd6d771e89fcc41d6f036608a7a036ca209c4b38e4ba4c0f346' 
  AND token = 'atAoyu8GUdXZtvUOiD4RZYGoa1GcP7WF5wfpNvZvBk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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