SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2506986975ff3ce66b1915436af1c7629587d7d0c5deb6b441c1f9f99676e2f4' 
  AND token = '9rBKhpXP15m9P2WmiUFgmUVtgUHq8aLJH1kHbzftZpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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