SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ef92327989c31c30797e450ae11e8e14ab66203c4b4236e121fe65bbe8c39f50' 
  AND token = '3jjKZVqZitAN/iYSGL+4M7Y6VJD9GOdItdgse7Iznx8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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