SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d7f7562a607c2393c94403901657227b13c89e5476ee5eb0e646dea6f734273' 
  AND token = 'dG6802EDBPPJ6JyZHpUfxESJhOKXz5PECYlNNWOMvCU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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