SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a18e0bf68ed0e637bf45467279d844279bc18c3dc9a43519b615dc43a801fae' 
  AND token = 'DFWjL11Fa8t7wD4iLhe0GyOo9RD5nMjEzPocGn1TwsQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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