SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0291bb1a3289bbc8ff489619b23f4b947a5b6f15db10d9b884a1c377c86d55ba' 
  AND token = 'u+QPznrfxgUIbZDHkQJgp/EHkUMpvmUvoA4hc5Jmy9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00012

JSON explain

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