SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a6343eb91f00972c2670cd10be6e589e6d92a7e6f928290f58b8d5326758b4a' 
  AND token = 'zmHWmONTNU9AuVStfPow9iZ8MJJFUp/W5hGnE+7zEHQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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