SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4b4f4b67bcebc6b8a7e96c59824f57f52f10946a62c9bbd508b84dad936b553' 
  AND token = 'By0GIyBVemwNQPaHeSv7FVRwbGURuNM2iY8zQblpwaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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