SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e65bbbe4bc777ae68923e02e2bbdeb93d0981d853e8c8803caaa96af03cc50c' 
  AND token = 'gRuXUTXzqrEu19MZWmYGaeNZ9S28uwoBRxJ6oLcRdXo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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