SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '789dac627695b3dbf4d58f77582b70cb57146cf03a09721d3a1902fc35b1ebfb' 
  AND token = 'GszDxwHt7UeMjJ/LNg+MfIPdREKWnts58D9jqCjtXw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}