SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '703f9dde984c22a565f9845ef5ea8068fa48a720e4a9192cef46fb49a4e1ea7b' 
  AND token = '86qyPfTyrMqEGYjo/VMqWQ6K1MtRP/nL4/W5DUu2OMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}