SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b53d84589377869397b859c6c85174cfd9b8134cdc83cd71204d5534f0f8d94' 
  AND token = 'iYYg573nwcCLNCOzgCUBOPdwWWkCuu8YzIrwyRKvE0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00093

JSON explain

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