SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55080e14ec96d7c251598f000380bd19815171ceb55e88752efc30d39fe0755b' 
  AND token = 'n4DzDfmv88Snu+3aReEZ2atyE1kN7X5Id5OEhw6r8sI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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