SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e6f1878aba2052d781b2eed52cbae5eefe030657e014b0015af78851d50417f' 
  AND token = 'or6CBPQz3bA/eLC7RB5/WkbhMREGXQPYOoWfmB5BZfg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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