SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f5914743b3b683b71f656d65ca43faea89e3afce924ccab555e550241d7ba18' 
  AND token = 'FigrLwe0OOC1z7ViFUZhS1b7SGKutvqrkYp3fVS6WgY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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