SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '68c0cf7d135c56bd38b09f137a8509729fde54cb7e6fcaa885193c8b018d2213' 
  AND token = 'MguL0wYN6YoTnSqBGfNEf3Zo302U+QaBzIVYRmwQ5Wk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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