SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8346f9a6a0dff98c7852612641f00f9f8f6375710dd18fa1dcde1234abe4f6e6' 
  AND token = '0FEmiIb2VZlvHThRBWh4lhKoDH8zojRzUNch+3oEJrw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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