SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '380e184e39aed432d63a4188ddb4f39bc8fb5550971477f0dd77182ece173299' 
  AND token = 'jQgLm+WVBxBjuSdVbRzcf81oXNOFtboOm+ebB8fzAUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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