SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6214c8c5af5c5ae8e21ee8bed8c3b738cdfdc8b4b9c2ad6347793a556949e7cc' 
  AND token = 'FxSbvbatVSH46TJu/zQJR3Wo7SE9bgUrCg3v8K+8NFQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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