SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16a1c7635d43ab4aeefabdea1574beaa34270e9802daad6038175663fffd8f6f' 
  AND token = 'SEVofC5cMDlKRVM0j5STlI+r6xy6ANylqiqettHUgEg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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