SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c9ad4f3dad836b2cbb9b903ceb64333c4394068c1fe652d766ddb778d09233e' 
  AND token = '0KQ4gLt9KRMpkd74ar7eYEQdqRSolylbwoc9JXIGUZo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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