SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad8a5aed29409df5403a6e94ba25db6701c8f459db3c3716ca3d7851fed44742' 
  AND token = 'LBY78Kl2LB9W67RuJAwmm6SHGctBKz/jHouziOHzw58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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