SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5503794aa4a74fc466cb29aa9e53d1c86c0f5f0b9b87bd1dd490e725db82646d' 
  AND token = 'eRwj5UEdY5Sd01c0eSXkuhfBBumtQzrRtVv1yKR/nAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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