SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3febf51ea73eaf5432ad43180663c836d28bcb7e7b640671d8105d79f8fd8c08' 
  AND token = 'f91zw11yhPuoxVww9pPf6TNTE5CmZ1/TW85xfjwV66Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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