SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3afbf3fdd81add71713ad7a79c62a16c6542c059342dece5444a5b1d87d85bb9' 
  AND token = '3VHPKUVVpmT/tEe/ZyFmJf5sTPu1gOj5w9xRkFxIRCs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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