SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9d21550e975a9dc0c9b0bf47b741fdff79e9de56c136136b1e4b04f39e912df7' 
  AND token = '9vxZ4zQMO4h44JgYeh0BTcGG27IApo+BHta1IcQfRkE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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