SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '506357a6c2e5fbf528264d80eeb52db55643cc888dc6f754c165f22c78e08254' 
  AND token = '1OlpxnuxpOy4jQDIyfFAaOvVPBxTZnuKGO1oZ/DLsKk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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