SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '909dd5b51e9a5a249dee6519a81ba1fe4fe8dd90bbe6a2bdf225692accf16cbc' 
  AND token = '/6tVTTHvXjiPDWNCMXUwB1HvMDCPgrTrISTkXirmYJs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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