SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8157f08b0cf1e840c266ce9b54dc87633e9822627034aa57f8d8b1d81bda2108' 
  AND token = 'pOG9MBSMk8bbDdwIX/RXFZ5zwFNAIHsjra0p++9CafY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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