SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '390fa941066625c244f53cb4f3770b50bd968bad4b2d8c7cdea1bb9a83cb2793' 
  AND token = 'rWcq5sW7y2mdWG8wrvouPj56VaN63lD2Lxn9A+n3ZHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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