SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8aa3b4f3dc29e43400de6f80ad7d6f3a4c9042681aa205227e6136cfdba4cfcc' 
  AND token = 'hS2WaHRJZrQS+H/S0EZ0WINvvF0HQGBABivDvo+ywl0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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