SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3eb988d42c50a05b68e748bc449a2e5d0f249effb06a9b8b194b6896dabbe2c4' 
  AND token = 'nuOAAtvOFO3KwTp04bku0ogfXTJtcXAZxwHr9lYZN+A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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