SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6ef4a0dc7fc1e59da0b592d54cacda9fa78b27c581946fd250855f24ae728d23' 
  AND token = '/uEAzKtgP46OVlxhO4BbNnmtuzD72B+2DVbcVk9xYjw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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