SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '971803b61dee8266fa42dd4b8e097053c0a6709f4fb541ce0bff7702f69b2400' 
  AND token = 'yfXXkqZZAnmL/Uxz+qVWYOVU+F81i74CBKHcyG+Jwr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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