SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a7ec275656270c8d78287c633d714fd2a47f2a849a1bd55362264ed2c4a87b2' 
  AND token = 'kHRThZIpNVEyKhz16MdzzIGaXn4hSqySeTx1y85dDlI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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