SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab741f4e75effbbb02d5127faf4c921017299fa8fae532c6efd3a11aeb5644e4' 
  AND token = 'uvIpfcv3pTeabF7bFMOCGw7bHnusRN+c3bOIm/8/HQ4=' 
  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"
    }
  }
}