SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7c7537d8cee9b8f07b342840908f84f2629aa1ef0864ffe0c8398a55badc732' 
  AND token = 'RGFyuOy8ibXvzyfjQZ8dMhvxt/cGLRGLvFA41A00fd8=' 
  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"
    }
  }
}