SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3cc43a502e6a032cec1d41d224d232643b7a184c21f35e92890d88fff98fdf9' 
  AND token = 'bQykjBc8nlCy5ECerdWbDNRBgW4aQTR/ZjGOY6RMf/0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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