SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cfc21e5c18164837aacd86a39616f5d319ca00f72bdc92b44c025b2cedc36bc' 
  AND token = 'JRAcXac2+kjk3vHZg+rZtNCW+KHDsynKySU/imyHLAc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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