SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f99135a24bfb56ed644b0aff51d95b436ea06c350f6445538f32365ad3dd84d' 
  AND token = 'mM455pq69i6UidoMm5tSZ9zeOMgXwO1c7Hsoj4pAxFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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