SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f706ca155f1ed31eff6ebbf4ccacf7fb2bb401c86e97d3edeee4857b6fdc8423' 
  AND token = 'N4jjAKHNoNP0oN8jzaL1DwO2OwtJtXLEGTDHmdmz81c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00013

JSON explain

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