SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd6415b2856513003952b2740d760027262dd4b3d13586e5199dc43cd20f9a62' 
  AND token = 'oIUpk2rwFK6PEY+YbIats0FvdzCn2CQMizV3htCnYAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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