SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '100b66390abe872f4cffdddf7c865a6fede32a4457a8216a21b215e9c1d576f9' 
  AND token = 'Fqo6wiaAUfhJi4OUPqlQ7XAgYxv+0ZtuxoDgmhKa4KE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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