SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '25d3fdcbcde2138bc6fd4163286984818c9734792024fcc4976109feb5c4d414' 
  AND token = 'xSbp1NsFwPnG1SmDu0zyjuEAYeU6jWtAYMLQVmUWw9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}