SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '284462a712042d0a45816bb7e13f299de44962576fd0841c3e1d779048228e1a' 
  AND token = 'ZOmnO/9tj4tQKDIqb4IyLluu/JXelF6b9YghGXfsm1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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