SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42ccb1ab5410bdf42558e2232c5574b84ecd426fc7db54218f7c537e8c1ed42e' 
  AND token = 'uvWc3IEwjsNfKyyUhMTa6tlY//Vi16HM5CKyJQjzxss=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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