SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d720671273181c7d6d3998c88f2ce4266996c0754ecd0b52d192da26357f516' 
  AND token = 'HiUwaJNr2aHl28SXJnPwtUNRthUiKbevlRDs5+nlLfs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}