SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '571e8de688da2b583c5f5cacd61b618d46f5c41e7319222d721a8ed50b0966d6' 
  AND token = 'QpZXMJVsuw3KZugdnT0hvb7mbkPnm6Hw/lynezxnkVk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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