SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b747cbaa138403042d8e7d59e4e9acfe74a78ed8dd59e254b3e70b8897261d7' 
  AND token = 'de8UlM1+EfIYyCcN1SkI9WSCpV8i1TvBt9ciHWvjUdM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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