SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '534e39c05d3655946c59d78188e1159c63e2f88aff2e06b32d47017e254c250b' 
  AND token = 'ROiCMqoRsLZRXrLfEKFatFnYkyPJJgLTiiVxHv68c9o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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