SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '642fb93db8edebd9df40306b4ff207bda675cac94032a184825fc13551157b80' 
  AND token = '/2PRgW7M4jAPQ5RQBXv3VxFoXFRmRjQrzAGAaKXg7Rg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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