SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb114c20b34cbc49958b13e77ca5d395e6921f183bce7cefb6cdc6b65adb57d2' 
  AND token = '5u6rgOXH+3xoXVvurSkjm6AYWRhVb8tGbBsRRhlU1Jw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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