SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ab8f00f82b8eaf097472462ddf89527f7a83d6a58bbbfc2b24d1a02358a7e2a' 
  AND token = '/DiWKO5AgZ/YsTtwF/Guvuq/jXrB+WFhBWN97ohCChs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}