SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8f6f679055b8bb604a7773719f539b0fa803391d2ace06d4aca39044b08c074' 
  AND token = 'Ol9FQJ4jgqWRwqrj7daMK/pLdopUJlHIGazNh+6GG8o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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