SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbfdfde08203dc3da6214f8c3e9d410a8e13b00b986cb968a8de769e8038da36' 
  AND token = 'WUEMGqGbbeQ0lmKAcacjJAe0HTmGuh2zVrSnKSLjkQw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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