SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef48a8b808bc9eae1b553d9987d485eb8fb5ea6fa34a153f816d567d3c7a1944' 
  AND token = 'H6gDVmsYjsZz34fPKum9vkVV3ursj1RycVYzn2R34lY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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