SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a8ec7fdeaaa1a16ca2f183735ea2dc5ebd76846dcb4ec06c6a40494bf75d37e' 
  AND token = 'zBH+KB4wzFhuaEmjBp3GbpTGS/XNjTdGq275PQRYUQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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