SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '3e276584c7f7eb362b7144b28393105c91c0407441d269c9b1c259960ae99011' 
  AND token = 'gMfwfCfeUvfEuDcyMkTz4BXWKWHO8pRUFjiTPwmOq4E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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