SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6083c486a238808bcc3088502725b29b699ed1fc685e406dd0c81743739e458' 
  AND token = 'xhnDbYD/JlSPF27lUz5KqZOCPuA6wQverVDVm756FEo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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