SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'e0cd7ba6eacbcaf720a114b3c380b575f4100f3894abe7de9bb45ec002bb2d0a' 
  AND token = '2y/kmJIgEVkt7YfVGoDAzgYxx+hxbs+d0lmmpdZ1ZFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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